lkml.org 
[lkml]   [2000]   [Oct]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: A patch to loop.c for better cryption support
    Date
    kernel  wrote:
    >There are some who believe that "not unique" IVs (across multiple
    >filesystems) facilitates some methods of cryptanalysis.

    It's a not a matter of "belief"; it's a matter of fact.
    The weakness is that the first block of ciphertext depends
    only on the IV and the first block of plaintext.

    Thus, if the IV is the same for two sectors, then you can
    tell from the two ciphertexts whether the two plaintexts
    start with the same 8-byte (or 16-byte) prefix. Since what
    we're encrypting is often patterned, and thus repeats in
    the beginning of the plaintext may be semi-common, this is
    not so good.

    The right thing is to use non-repeating, unpredictable IV's.
    One way to do this is to use E_k(sector number) as your IV,
    as I mentioned earlier; or, if you want relocatibility, you
    could use E_k(sector number + seed).

    Ask on sci.crypt if you need more specific advice.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 12:41    [W:0.021 / U:0.304 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site